As we know, "nod" pronounces /nɒd/ while "node" pronounces /nəʊd/ (In US style?).

So why does the extra "e" change the vocal of letter "o" entirely?

My mother language is Chinese, therefore, it seems to be little hard for me to understand the exact rules of pronunciation with respect to spelling. What resources (maybe books?) can I invoke if I'd like to precisely predict how a coined word or the one which is unfamiliar pronounce?

English spelling is notoriously unpredictable. So in the end you will have to look up a word in a dictionary to make sure you pronounce it correctly. But this difference in sound between -/ɒd/ and -/əʊd/ is very common for words ending on -od and -ode, respectively, so this will help you predict the pronunciations of words such as lode, sod, code, pod, etc. Similarly, there are the pairs id/ide, ad/ade, ud/ude, and ed/ede.
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CerberusJan 25 '13 at 5:25

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US style would be /nad/ and /nod/. American /o/ has [ow] (not [əw]) as the principal stressed allophone.
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John LawlerJan 25 '13 at 5:34

1 Answer
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The "extra e" (or "silent e") at the end of a word is a convention which serves as a sign that the precedingshort vowel should be elongated into a long vowel. It was introduced by Richard Mulcaster in 1582 via his book Elementarie wherein he called it a "qualifying e". The Wikipedia article on the "silent e" makes for fascinating reading.

The rule is, however (and as with most aspects of English orthography), inconsistently employed. While node, side, and rate all involve long vowels, words such as love, give, and sieve do not.